使用Mockito创建新类的实例时如何模拟异常 [英] How to mock an exception when creating an instance of a new class using Mockito

问题描述

在一个方法中，有一个我要模拟的异常被捕获.

Within a method, I have an exception being caught which I want to mock.

我知道如何使用ock.doSomething()模拟对象以引发异常，但是当类创建其自身的新实例时，我需要引发远程异常.

I know how to mock an object to throw an exception using mock.doSomething(), but I need to throw a remote exception when a class makes a new instance of itself.

transient Bicycle bike = null;

public Bicycle getBicycle() {
    if (bike == null) {
        try {
            bike = new Bicycle(this);
        } catch (RemoteException ex) {
            System.out.println("No bikes found");
        }
    }
    return bike;
}

我希望能够模拟try块中的所有内容，但我不理解您如何模拟新类的创建，具体如下几行:

I want to be able to mock everything in the try block, but I don't understand how you mock the creation of a new class, the following line to be specific:

bike = new Bicycle(this);

我尝试了许多不同的Mockito测试，例如:

I have tried many different Mockito tests, such as:

Bicycle b = mock(Bicycle.class);
Mockito.doThrow(new RemoteException()).when(b = new Bicycle());

尽管我知道这会并且不起作用，但我想做类似的事情.

Although I understand this will and is not working, I want to do something similar.

我已经阅读了Mockito文档，但没有发现有用的东西:

I have read the Mockito docs and haven't found anything useful:

http://site.mockito.org/mockito /docs/current/org/mockito/Mockito.html

推荐答案

在这种情况下，您可以使用Mockito扩展程序PowerMock.它允许模拟构造函数(请参见 https://code.google.com/p/powermock /wiki/MockConstructor ).

You can use a Mockito extension, PowerMock, in cases like this. It allows constructors to be mocked (see https://code.google.com/p/powermock/wiki/MockConstructor).

在这种情况下，您将编写类似以下测试的内容:

In this case, you would write something like the following test:

@RunWith(PowerMockRunner.class)
@PrepareForTest({ClassUnderTest.class, Bicycle.class})
public class ConstructorMockingTest
{
    @Test
    public void getBicycle()
    {
        ClassUnderTest tested = new ClassUnderTest();
        whenNew(Bicycle.class).withArguments(tested).thenThrow(new RemoteException());

        Bicycle bicycle = tested.getBicycle();

        assertNull(bicycle);
    }
}

更多示例可在以下位置找到:

More examples can be found at: https://code.google.com/p/powermock/source/browse/trunk/modules/module-test/mockito/junit4/src/test/java/samples/powermockito/junit4/whennew/WhenNewTest.java

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